intriguing v.support error

Susan Huse sue at ced.berkeley.edu
Tue Jun 21 14:39:46 EDT 1994


Hi, just thought I'd see if anyone has ever had a similar
experience.

I have been working with a shoreline vector file.  I wanted
to do some cleaning up of it.  The file is basically an outline
of the San Francisco Bay shoreline.  Very fine point density, the
line type is area edge, though there are few closed polygons,
just a few islands.  The file is about 1.6 megabytes.

I was working on it at one location and it was running too slowly
so I used tar to dump to a tape and transfer it up to campus
where I could use a Dec Alpha.  I did this same procedure for 3
of these files (I had broken the bay into 3 segments, so the file
size would be more manageable, all are in teh range of 1.5 mb).
Two of the files transferred fine,  the third would give error
messages on v.support.  It would tell me it was converting from
GRASS3 to GRASS4, then happily run v.support and give me an empty
dig file (0 bytes).  It was NEVER in GRASS3 format, and the other
two (which came from the same root file) did not have this message.

I could run v.support successfully on the Sparc I had been using, 
so I just thought there was some odd tape transfer problem.  Even
though it happened more than once, and in both directions (from
location a to b and back to a).

Later I had taken some vector files and wanted to patch them in
to the shoreline file.  (No tapes involved).  It patched fine, 
ran v.support fine, then I tried to use v.spag.  YOUCH!!  It
ran for several days before filling up the entire disk and crashing
for lack of memory.  After the patch (before v.spag) the file was
still less than 2 megabytes.  It had exploded to 35 megabytes when it
ran out of space.  I decided not to use v.spag for this particular
file.  v.spag has been running fine on that system before and since.

Then I decided to edit by hand.  I did a fair amount of work on
it, breaking, snapping, removing, etc.  When I broke for the evening
I quit v.digit and ran v.support.  Hmmmmm.

It did it's usual "loading vector file"  
10% 
20%
30%
etc.

I went away for a little while and then it was COUNTING DOWN!!!
-90%
-80% 
-70%


I was amazed!  NEVER seen anything like that one!
I can't remember how it crashed, I think the file exploded again
or perhaps v.support just crashed directly.  But I lost the file
entirely.


I have since decided to not use the shoreline file (oh, gee, 
how long did that take??)  But was curious if anyone had any
ideas what was going on and what type of data bug could cause
the explosions, the 3 to 4 conversion message, and the countdown.

-Sue Huse
REGIS
UC Berkeley



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